There are concerns that the partnership may not last. The two men have been locked in a personal feud since Mr. Ponta tried, but failed, to impeach the president in July.

The prime minister now has 10 days to form a new government.

EU officials have accused Mr. Ponta of undermining the rule of law and voiced concern the feud between the two would bring more political turmoil to the EU's second-poorest state, which is struggling to recover from tough austerity measures.

Romania took out a $26-billion bailout loan from the International Monetary Fund and the World Bank in 2009 to help pay pensions and salaries.